Many satellites and other spacecraft, as well as some terrestrial stationary and vehicle applications, such as seagoing vessels, can include one or more energy storage flywheel systems to provide both a backup power source and to provide attitude control for the vehicle. In such systems, each flywheel system is controlled and regulated to balance the electrical demand in the vehicle electrical distribution system, and may also be controlled in response to programmed or remote attitude (or torque) commands received by a main controller in the vehicle.
Many energy storage flywheel systems include one or more components that are rotationally supported within a housing assembly. These components, which may be referred to as the rotating group, include, for example, an energy storage flywheel, a motor/generator, and a shaft. In particular, the energy storage flywheel and motor/generator may be mounted on the shaft, which may in turn be rotationally supported in the housing assembly via one or more bearing assemblies. In many instances, the shaft is rotationally supported using one or more primary bearing assemblies, and one or more auxiliary, or back-up, bearing assemblies. For example, in many satellite and spacecraft applications, the flywheel system may include one or more magnetic bearing assemblies that function as the primary bearing assemblies, and one or more mechanical bearing assemblies that function as the auxiliary bearing assemblies. Typically, the primary bearing assemblies are used to rotationally support the rotating group, while the auxiliary bearing assemblies are otherwise disengaged from the rotating group. If one or more of the primary bearing assemblies is deactivated due, for example, to a malfunction, or otherwise becomes inoperable to rotationally support the rotating group, the auxiliary bearing assemblies will then engage, and thereby rotationally support, the rotating group.
When the auxiliary bearing assemblies engage the rotating group, the rotating group is, in many instances, rotating at relatively high speeds. During spin down of the rotating group, the auxiliary bearing assemblies may be subject to vibration as the rotating group rotates through certain speeds. Many of the auxiliary bearing assemblies presently used may not be configured to handle or dampen some of these vibrations. Thus the bearing assemblies, or other system components, may be damaged or worn. This can shorten system lifetime and increase overall system costs. Moreover, many of the auxiliary bearing assemblies may be constructed of materials having different thermal coefficients of expansion than the rotating group, as may many of the components that make up the rotating group. Thus, tolerances between the bearing assemblies and the rotating group can change with temperature. This can also lead to increased wear rate and/or damage, which can additionally lead to shortened system lifetime and increase overall system costs
Hence, there is a need for an auxiliary bearing assembly that improves on one or more of the above-noted drawbacks. Namely, an auxiliary bearing assembly that is configured to absorb and/or damp out vibrations from the rotating components following engagement thereby of the auxiliary bearing assembly, and/or that can absorb differential thermal growths between rotating and stationary components. The present invention addresses one or more of these needs.